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Lowest-impact meat still has a higher footprint than vegetable proteins (Photo: CC0)

Giving up meat and dairy products is the single most effective way to reduce your environmental impact, new research has revealed. According to a comprehensive analysis published in the journal Science, livestock only provides 18% of calories and 37% of our protein while taking up 83% of farmland worldwide. The scientists at Oxford University and Swiss agricultural research institute Agroscope found that switching to a vegan diet could reduce a person’s carbon footprint by as much as 73%. If everyone went vegan, we would require 3.1 billion hectares less farmland. The focus of the study was to assess the environmental impact for 40 different agricultural goods around the world in a meta-analysis comparing various types of food production systems. The researchers created a database on the environmental impacts of 38,700 farms as well as 1,600 processors, packaging types, and retailers. In order to assess the different environmental impacts, they looked at five environmental indicators: land use, climate change emissions, freshwater withdrawals and water pollution (eutrophication), and air pollution (acidification).

The scientists found large differences for one and the same product. “Impact can vary 50-fold among producers of the same product, creating substantial mitigation opportunities,” says the abstract. For example, one pint of beer can create 3 times more emissions and use 4 times more land than another. High-impact beef producers create 105kg of CO2 equivalents and use 370 square metres of land per 100 grams of protein, causing 12 times more emissions and using 50 times more land than low-impact beef producers, with dairy herds grazing rich natural pasture. High variation within and between protein-rich products is also manifest in acidification, eutrophication, and water use. “Two things that look the same in the shops can have extremely different impacts on the planet. We currently don’t know this when we make choices about what to eat. Further, this variability isn’t fully reflected in strategies and policy aimed at reducing the impacts of farmers,” said lead author Joseph Poore.

The study also showed that animal product free diets delivered the greatest environmental benefits. The impacts of even the lowest-impact animal products still exceeded those of vegetable substitutes, providing new evidence for the importance of dietary change. For example, tenth-percentile greenhouse gas emissions of dairy beef were 36 times higher with 9.1 kg CO2eq per 100 grams of protein than those of peas with 0.25 kg CO2eq, including all processing, packaging, and transport. In addition, the lowest impact beef used six times more land (7.3m²) than peas (1.2m²). A low-impact litre of cow’s milk uses almost two times as much land and creates almost double the emissions as an average litre of soymilk. “Moving from current diets to a diet that excludes animal products has transformative potential, reducing food’s land use by 3.1 billion hectares (a 76% reduction), including a 19% reduction in arable land,” the authors write. “This would take pressure off the world’s tropical forests and release land back to nature,” said Joseph Poore. The researchers also found that plant-based diets would reduce food’s emissions by 6.6 billion metric tons of CO2eq (a 49% reduction); acidification by 50%, eutrophication by 49% and freshwater withdrawals by 19%.

But reducing the environmental footprint of food production would also be possible without everyone having to go vegan. The researchers showed that reducing the consumption of animal products by 50% by avoiding the highest-impact producers could achieve 73% of the greenhouse gas emission cuts a switch to plant-based diet’s would result in. Further, lowering consumption of discretionary products (oils, alcohol, sugar, and stimulants) by 20% by avoiding high-impact producers would reduce the emissions caused by these products by 43%. “Agriculture is characterised by millions of diverse producers. This diversity creates the variation in environmental impact,” said Poore. However, this heterogeneity creates opportunities to target the small numbers of producers that have the most impact. “We need to find ways to slightly change the conditions so it’s better for producers and consumers to act in favour of the environment,” says Joseph Poore. “Environmental labels and financial incentives would support more sustainable consumption, while creating a positive loop: Farmers would need to monitor their impacts, encouraging better decision making; and communicate their impacts to suppliers, encouraging better sourcing.” (ab)